Preparation of halo-olefin

Abstract

A process for preparing a halo-olefin to minimize one or more side reactions which form at least one impurity, said process comprising contacting a halogenated hydrocarbon with a metal dehalogenating agent dissolved in a solvent under conditions sufficient to dehalogenate said halogenated hydrocarbon to produce a product stream comprising said halo-olefin and at least one impurity, said metal dehalogenating agent having an average particle size within a range of average particle sizes, said impurity concentration of said product stream being essentially constant within said range and increasing significantly below said range.

Description

FIELD OF INVENTION[0001]This invention relates to the dehalogenation of a halogen-containing compound. In one of its aspects, this invention relates to the dechlorination of a halogenated organic compound. In one of its more particular aspects, this invention relates to the dechlorination of trifluorotrichloroethane to produce chlorotrifluoroethylene.BACKGROUND OF INVENTION[0002]Intermediate compounds of significant industrial importance are prepared by the dehalogenation of saturated halocarbons. For example, polytrifluorochloroethylene is prepared by the polymerization of trifluorotrichloroethylene, an intermediate which is prepared by the dechlorination of trifluorotrichloroethane.[0003]In a well known process, chlorotrifluoroethane (CTFE-1113) is produced by reacting a halogenated starting material, specifically, trichlorotrifluoroethane (CFC-113), with a metallic dehalogenation agent, such as zinc dust. (In this particular reaction, zinc chloride is produced as a co-product of ...

AI Technical Summary

Benefits of technology

The patent text describes a process for making halo-olefins using a small particle size agent that improves yield but reduces side reactions. By controlling the particle size of the agent, the process can minimize side reactions and impurities, which makes it difficult to meet product quality specifications and increases distillation yield losses. The text also suggests that using an agent with larger particle sizes can improve processability and reduce costs. The technical effect of the patent is to provide a more efficient and economical process for making halo-olefins with reduced side reactions and impurities.

Problems solved by technology

The increase in side reactions and the impurities they form makes meeting product quality specifications difficult, and increases distillation yield losses.

That is, by way of contrast, lower sizes of particles tend to result in increased handling difficulties due to the tendency of the material to “clump,” thereby resulting in process downtime due to plugged piping and vessels.

For example, with respect to zinc, sizes above 5 microns may not be considered premium quality since they are not suitable for pigments in paints and, thus, are less expensive.

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